B0FieldSource as a list

[mateuszpawlik]

Describe the bug If multiple fieldmaps are used for one functional image, the B0FieldSource should be a list. We're having trouble to compose that list in the mapping file. We used the yaml syntax but it seems not to work.

The log of bidscoiner doesn't have any entry for B0FieldSource under functional files.

To reproduce Use something like this in the mapping file

B0FieldSource: 
  - magnetude1
  - magnetude2
  - phasediff

Expected behavior B0FieldSource key with JSON array is added to the functional json files.

Software version

• BIDScoin version 4.2.1
• OS Debian 11

[marcelzwiers]

I'm not sure if I understand the problem, as the BIDS specification defines just a single tag, not a list, right? So

B0FieldSource: 
  - tag1
  - tag2
  - tag3

should be converted to

B0FieldSource: tag1tag2tag3

???

[marcelzwiers]

B0FieldIdentifier | RECOMMENDED | string or array of strings

Aha, I didn't know this, I'll see what I can do

[mateuszpawlik]

BIDS specification says that it's a string or an array of strings. I don't really know how tools should use it, but with IntendedFor we can say that we use three fieldmaps for one functional image.

[marcelzwiers]

I guess you can pass a list like this?

B0FieldSource: [magnetude1, magnetude2, phasediff]

[mateuszpawlik]

Should be fine but it shouldn't matter both forms are correct syntax.

[marcelzwiers]

Yes I know, but I mean that's how you can pass it in the bidseditor?

[mateuszpawlik]

Ah, I'm not using the BIDS editor :see_no_evil: But if I did, I'd be fine with the compact syntax.

[marcelzwiers]

I just tested it and, except for the <<session>> value, it worked just fine? In the template I did:

    meta: &fmap_meta
      B0FieldIdentifier: [tag1, <<session>>tag2]

And then I got this in the json sidecar file:

    "B0FieldIdentifier": [
        "tag1",
        "<<session>>tag2"
    ]

[mateuszpawlik]

Looks fine to me. I can try to test more next week (with the <<session>> tag) as we're planning to upgrade to BIDScoin 4.3.0 and test some mappings.

[marcelzwiers]

Actually, entering [tag1, <<session>>tag2] in the bidseditor is interpreted as a string, so that doesn't work (but then <<session>> does), giving for sub-001_ses-01_acq-fieldmap2p4iso_magnitude1.json:

    "B0FieldIdentifier": "[tag1, 01tag2]"

[marcelzwiers]

NB: passing ["tag1", '<<session>>tag2'] in the bidseditor correctly (besides <<session>>) gives:

    "B0FieldIdentifier": [
        "tag1",
        "<<session>>tag2"
    ]

[marcelzwiers]

Please reopen if things are not working for you